Trimmed Mesher

This repository contains a C implementation of a trimmed mesher designed for Computational Fluid Dynamics (CFD) simulations. The mesher generates a cartesian 2D conformal grid composed of square cells and adapts it to incorporate an embedded closed curve, representing an obstacle within the flow domain.

In addition to the core meshing algorithms, this project includes a Python-based GUI built with CustomTkinter, which provides an easy-to-use interface for users to interact with the mesher, without the need for command-line interface (CLI) knowledge.

Key features of the project include:

• Semi-cartesian conformal mesh generation for accurate CFD simulations.

• Near-wall cells optimizations for accurate simulations of boundary layers.

• Smoothing algorithms to improve mesh quality.

• External coarsening for large simulation domains.

Usage

Input curve format

The input curve must be provided as a CSV file with X, Y coordinates separated by a comma. The file should represent a closed polygonal curve. It is important that there are no duplicated points in the curve, as the program will rely on unique points for mesh generation. Here’s an example of the format:

X1, Y1
X2, Y2
...
XN, YN

Output mesh file

The generated mesh will be saved in the GMSH ASCII format (version 2.2), which includes both nodes and elements. This format is widely used and can be further processed in simulation tools like GMSH, OpenFOAM, and others. Here's an example of the output structure:

$MeshFormat
2.2 0 8
$EndMeshFormat
$Nodes
<node data>
$EndNodes
$Elements
<element data>
$EndElements

Building

Requirements

• C compiler (e.g., gcc, clang, etc.)
• Standard C libraries (stdio.h, stdlib.h, math.h)
• CMake (version 3.10 or higher)
• git (optional, for version control)
• Python 3.6 or higher (for the GUI)
• Python virtual environment (for managing dependencies)
• PyInstaller (for building the GUI executable)

Compiling the Core

To compile the C code, navigate to the project directory and use the following commands:

mkdir build
cd build
cmake ..
make

The compiled executable will be generated inside the build folder.

Building the GUI

To build the GUI, you first need to install all the Python dependencies. To do so, follow these steps:

1. Create and activate a Python virtual environment:

python3 -m venv .venv
source .venv/bin/activate   # For Unix/macOS
.venv\Scripts\activate      # For Windows

2. Install the Python requirements:

pip install -r requirements.txt

3. Install PyInstaller to build the GUI executable:

pip install pyinstaller

4. Navigate to the gui folder in the project directory:

cd gui

5. Build the GUI executable using PyInstaller:

pyinstaller --onefile --windowed \
  --add-binary "../build/mesher:mesher" \
  --add-data "theme.json:." \
  --add-data "images:images/" \
  --add-data "../.venv/lib/python3.x/site-packages/PIL:PIL/" \
  --icon=images/icon.png \
  -n "Trimmed Mesher" --clean gui.py

Make sure to replace python3.x with the version of Python you are using (e.g., python3.12).

The executable file will be created in the gui/dist folder.

License

This project is licensed under the Apache 2.0 License. See the LICENSE file for details.